Apparatus for producing a collimated beam of radioactive rays



AFPA' us Fon Pnonu Feb.17, 1970 .J. RADCLIFFE ETAL 3,496,361

CNvA JJIMATED Y 9 BEAM 0F RADIOA T E Original Filed Sept. 12, 1961 3 Sheets-Sheet 1 I'IllI I'III': 43 441 4^ Il( 5 50 fl ""I "TF Uhh l DANIEL E IHAVEL Feb. 117, 1970 12J. RADL|F`FE ETAL 3,496,361

APPARAT US FOR PRODUCING A COLLIMATED BEAM QF RADIOACTIVE RAYS Y Qrignal Filed Sept. 12, 1961 3 Sheets-Sheet 2 I INVENTORS THOMAS J. RADCUFFE DANIEL M.MELHA-EY,JR. )NIELEHAvEL ATTO KN EY .Feb. 17, 1970 'r. J. RADCLIFFE ErAl. 3,496,361

APPARATUS PRODUCING A COLLIMATED BEAM RADIOACTIVE RAYS Original Filed Sept. 12, 1961 3 Sheets-Sheet 3 THO S J. ADCLIFE DANIEL M. MQELHANBLJR.

ATTORN! EY United States PatentV O 3,496,361 APPARATUS FOR PRODUCING A COLLIMATED BEAM F RADIOACTIVE RAYS Thomas J. Radcliffe, Warrensville Heights, Daniel M.

McElhaney, Jr., Euclid, and Daniel F. Havel, Cleveland, Ohio, assignors to Republic Steel Corporation, Cleveland, Ohio, a corporation of New Jersey Original application Sept. 12, 1961, Ser. No. 137,588, now Patent No. 3,304,241, dated Feb. 14, 1967. Divided and this application July 7, 1966, Ser. No. 563,515

Int. Cl. G21f 5 /02 U.S. Cl. Z50-105 4 Claims ABSTRACT 0F THE DISCLOSURE A block of radiation absorbing material having a first bore extending inwardly from a point on the external surface of the block and meeting a second bore extending inwardly from another point on the surface. The two bores may be diametrically opposed so as to make up a single bore, or they may meet at an angle. A bolt is inserted threadedly in the first bore. The bolt has a rescess near its inner end holding a source of radioactive rays. When the bolt is in place, the source is aligned with the second bore. A thin plug may be placed in the outer opening of the second bore. The plug is permeable to radioactive rays and serves to prevent entrance of dirt into the bore. This plug is replaceable rby a thicker plug of absorbing material which serves to block radiation completely. The block is mounted between a pair of parallel plates connected by through bolts. The block may be cylindrical or it may have spherical shape such that it may be rotated universally between the plates. A shutter pivotally mounted on one of the through bolts lmay be provided so as to block the radioactive rays in one position, and to allow free exit of rays in another position.

The present application is a division of our copending application Ser. No. 137,588, filed Sept. 12, 1961, entitled, Safety Control Apparatus for Coke Oven Batteries, now Patent No. 3,304,241, issued Feb. 14, 1967.

There is disclosed in our parent application safety control apparatus useful in situations where the atmosphere is smoky or foggy, such as in the vicinity of coke oven batteries. That apparatus includes holders for sources of radioactive material which are capable of directing collimated beams of radioactive rays toward appropriate ray detectors. The source holder and detector may be separated by a considerable distance and that distance may include a region subject to dense smoke and/or vapor conditions. The source and the detector are utilized to communicate to the detector the existence of certain conditions at the source. In one modification, the source is provided with a shutter actuated in response to controlling conditions so that the shutter blocks the beam of rays when the controlling conditions are unsafe and allows the beam to impinge on the detector only when the controlling conditions are safe.

In a second modification, the source holder is mounted on a vehicle, and no shutter is provided. The detector is mounted along the side of a track along which the vehicle moves, and the impingement of the beam of rays on the detector is utilized as an indication of the presence of the vehicle.

An object of the present invention is to provide improved source holders for radioactive materials used in safety systems.

Another object is to provide an improved source holder for producing a collimated beam of radioactive rays.

3 ,496 ,361 Patented Feb. 17, 1970 A further object is to provide, in such a source holder, an improved shutter arrangement for selectively blocking or unblockng the beam.

A further object is to provide, in such a source holder, liam proved means for varying the direction of the collimated earn.

The foregoing and other objects are attained in the apparatus described herein. That apparatus comprises a block of radiation absorb-ing material having a first bore extending inwardly from a point on the external surface of the block and meeting a second bore extending inwardly from another point on the surface. The two bores may be diametrically opposite so as to constitute, in effect, a single bore, or they may meet at an angle. A bolt is inserted in the first bore and] has a recess near its inner end adapted to recieve a source of radioactive rays, and a head on its outer end adapted to engage the outer surface of the block. The spacing along the bolt between the head and the recess is equal to the spacing through the first bore between the outer surface of the block and the second bore, so that when the `bolt is in place, a source in the recess is aligned with the second bore. A plug is inserted in the second bore near its outer end, the plug being relatively short so as not to block the radioactive rays and. serving primarily to prevent the entrance of dirt into the bore. The short plug is removable and replaceable by an elongated plug effective to block the rays completely. The elongated plug is used during shipment and on other occasions when the beam of rays is not to be used for a considerable period of time.

The block of material is mounted between a pair of parallel plates engaging opposite suifaces of the block and having margins projecting beyond the plug. A plurality of through bolts threadedly engage the Imargins and are adapted for connection to a suitable support.

In one modification of the invention, a shutter is pivotally mounted on one of the through bolts and is movable between a position in which it blocks the beams rays and another position in which the beam of rays is unblocked.

In another modification, the block is spherical and the parallel plates are provided with caps facing and fitting the spherical block. The block may be rotated universally between the caps upon loosening of the bolts to vary the direction of the collimated beam of rays issuing from the second bore.

Other objects of the invention will become apparent from a consideration of the following specification, taken together with the accompanying drawings.

In the drawings:

FIG. 1 is an elevational view of one form of radioactive source holder constructed in accordance with the invention;

FIG. 2 is a cross-sectional view taken on the line 2--2 of FIG. 1;

FIG. 3 is a fragmentary cross-sectional view similar to FIG. 2, showing a shipping bolt in the source holder;

FIG. 4 is a view partly in plan and partly in section, of the source holder of FIGS. l and 2;

FIG. 5 is an elevational view of another form of source holder constructed in accordance with the invention;

FIG. 6 is a plan view of the source holder of FIG. 5; and

FIG. 7 is a cross-sectional view taken on the line 7-7 of FIG. 6.

FIGS. 1 TO 4 These figures illustrate a source holder for radioactive material, mounted by means of four threaded stainless steel mounting rods 33 on an overhead frame (not shown). A source 35 (FIG. 2) of radioactive energy is received in a recess drilled in the end of a bolt 36 and is held in place in the recess by means of a set screw 37. A massive cylindrical block 38, preferably of steel, is provided with a vertical central bore 38a in which the bolt 36 is received. The block 38 is welded to upper and lower plates 39 and 40, through which the bolts 33 extend freely. Nuts 41 threaded on bolts 33, engage the upper and lower plates and fix the vertical position of the source holder. A nut 42 is welded on the outer side of the center of the upper plate 39 and threadedly receives a threaded portion of the shank of bolt 36. A sleeve 43 (FIGS. 1 and 4) is rotatably mounted on one of the rods 33 between the plates 39 and 40. The sleeve 43 and its associated bolt 33 serve as a hinge for a shutter generally indicated at 44. The shutter 44 comprises a steel plate bent in an L shape so as to have a short leg 44a and a long leg 4412. The short leg 44a is welded at its end to the sleeve 43. The leg 44b extends horizontally in front of a bore 38h (FIG. 2) provided in the block 38. The bore 38b at its inner end communicates with the bore 38a which receives the source bolt 36. On the outer side of the block 38 and encircling the bore 38h is welded a nut 45. When the radioactive source is operating a small plug 46 (FIG. 4) of aluminum, or other material transparent to the radioactive rays from the source 35, is inserted in nut 45. The plug 46 is provided to keep dirt and other foreign materials out of the bore 38b. On the inner face of the plate 44h is welded a ring 47, which, when the shutter is closed, encircles the plug 46 and the bolt 45, with its inner end abutting against the block 38. On the outer side of the plate 44b is welded a steel block 48 having horizontal dimensions sufficient to block substantially all the radiation from the source 35 passing through the bore 38h. The shutter, comprising the plate 44, block '48 and ring 47 is shown in FIGS. 1, 2 and 3 in its closed position, with the radiation blocked. To open the shutter, it is rotated n its hinge 33, 43, to swing the cylindrical block out of alignment with the bore 38h.

During shipment of the source holder 237 the plug 46 is removed and replaced by a bolt 49 (see FIG. 3), having a shank which substantially completely lls the bore 38b and effectively blocks any radiation proceeding through that bore from the source 35. The source is then substantially completely enclosed, regardless of any opening and closing of the shutter which may occur during transportation. The bolt 33 nearest the right-hand end of the shutter plate 44b, as viewed in FIG. 1 is encircled loosely by a sleeve 50 having welded thereon an arm 51 which projects forwardly as viewed in FIGS. 1 and 4 and extends through an opening 44C in the shutter plate 44b. Outside the shutter plate 44C the arm 51 is provided with a hole 51a to receive a padlock or other suitable fastening device for holding the shutter plate 44b in its closed position.

The locking procedure described above is commonly used only during shipment or storage of a source holder 23. The shipping bolt 49 shown in FIG. 5 is also used only during shipping or storage of the complete source holder 23. When the bolt 49 is used, then radiation from the source is effectively shielded, even if the shutter 44 is damaged or completely removed.

The radioactive source material 35 may be any suitable radioactive isotope. Cobalt 60 and radium have been successfully used.

The threaded rods 33 also provide a convenient means for adjusting the height of the source holder to secure alignment of the source with a detector.

FIGS. 5, 6 AND 7 These figures illustrate a modied form of source holder, shown generally at 27. The holder includes three threaded rods 150 which may be fastened to the roof of an underlying or overlying support by any suitable means. An upper plate 151 and a base plate 152 are slidably mounted on the bolts 1,50. Nuts 153 engage the bolts below the base plate 152. Similarly, nuts 154 on the bolts 150 above the upper plate 151 hold it against upward movement. The lower plate 152 has on its upper surface an -upwardly projecting annular flange 155, whose uppermost edge is beveled, as shown at 155g. The upper plate 151 has projecting downwardly from its under surface a similar flange 156, whose lower surface is beveled as shown at 156a. A sphere 157, preferably of steel, is clamped between the beveled surfaces 155g and 156a by tightening the nuts 153 and 154. The sphere 157 is provided with a diametrical bore 157a. Internally threaded nuts 158 and 159 are welded to the surface of the sphere 157 and encircle the opposite ends of the bore 157a.

The nut 158 threadedly receives a bolt 160- having a threaded shank 160a adapted to cooperate with nut 158. The bolt 160 has a hexagonal head 16011 and is provided with a projecting ring 161 at the center of the head to receive the end of a chain 162. The other end of the chain is Welded to the plate 151. The chain serves as a safety retainer to hold the source bolt 160 in case it should become loosened and fall out of the nut 158. The inner end of the bolt 160 is provided with a recess 160C to receive a source of radioactive rays. The recess 160C is threaded to receive a retainer screw 160:1. after the radioactive material is inserted. A plug 163 is threaded into the nut 159. This plug serves the same function as the plug 46 in the source holder of FIGS. 1 and 2. During shipment of the source holder plug 46 may be replaced by a shipping bolt similar to the bolt 49 of FIG. 3.

It may be seen that by loosening the nuts 154, the sphere 157 becomes capable of universal rotation on the flanges 155 and 156, so that the bore 15751, and particularly the end thereof containing the plug 163, may be aimed in any desired direction.

While we have shown and described certain prepared embodiments of our invention, other modifications thereof will readily occur to those skilled in the art, and we therefore intend our invention to be limited only by the appended claims.

What is claimed is:

I. Apparatus for producing a collimated beam of radioactive rays, comprising:

(a) a block of radiation absorbing material having a iirst bore extending inwardly from a point on the external surface of the block and a second radial bore extending inwardly from another point on the external surface of the block and communicating with said first bore;

(b) retaining means in said rst bore for supporting l.a source of radioactive rays in alignment with said second bore; and

(c) mounting means for said block; wherein the improvement comprises:

(d) a bolt in said retaining means comprising a head and an elongated shank having a threaded portion adjacent the head and `an unthreaded portion extending beyond the threaded portion and insertable in said first bore, said shank having a recess opening from the shank end and adapted to receive a source of radioactive rays;

(e) cap means to hold the source in said recess;

(f) a nut cooperating with the threaded portion of the shank;

(g) means in said mounting means supporting the nut with its axis aligned with the axis of said first bore; and

(h) the spacing between the head and the recess being equal to the spacing between the outer surfaces of the nut and the second bore, so that -a source in the recess is aligned with the second bore when the head engages said outer surface of the nut.

2. Apparatus as defined in claim 1, including:

(a) a pair of parallel plate means in said mounting means and engaging opposite surfaces of said block,

said plate means both having margins projecting beyond the block;

(b) a plurality of through bolts extending through said margins and having end portions adapted for connection to a support;

(c) nuts on said through bolts on opposite sides of the plate means from the block and clamping the plate means and the block together;

(d) said rst bore being parallel to the through bolts and said second bore being at right angles to the rst bore;

(e) a shutter for said second bore pivoted on one of said through bolts, said shutter comprising:

(1) a sleeve loosely received on said one bolt for pivotal movement thereon;

(2) a flat plate attached to the sleeve and extending parallel to the axis of the sleeve;

(3) a hollow cylinder on one side of the plate and extending therefrom toward the block, said cylinder being adapted to encircle the head of a plug in said second bore; and

(4) a solid cylinder attached to the outer side of said plate and aligned with said hollow cylinder, said solid cylinder being formed of radiation absorbing material.

3. Apparatus as defined in claim 2, including:

(a) -an arm mounted on another one of said through bolts;

(b) said iiat plate having a slot formed therein for receiving the end of said arm when the shutter is closed; and

(c) said arm having an aperture formed in said end for receiving a padlock.

4. Apparatus for producing a collimated beam of radioactive rays, comprising:

(a) a spherical block of radiation absorbing material having a bore extending diametrically through the block;

(b) retaining means in said bore for supporting a source of radioactive rays at the center of the block; and

(c) mounting means for said block;

wherein the improvement comprises:

(d) a bolt in said retaining means comprising a head and an elongated shank having a threaded portion adjacent the head and an unthreaded portion extending beyond the threaded portion and insertable in said bore, said shank having a recess opening from the shank end and adapted to receive a source of radioactive rays;

(e) cap means to hold the source in said recess;

(f) a nut 4welded to the spherical block encircling one end of the bore, and cooperating with the threaded portion of the shank;

(g) a pair of parallel plate means in said mounting means, said plate means engaging opposite surfaces of said block and extending beyond the block, each said plate means comprising a concave cap facing and tting said spherical block;

(h) a plurality of through bolts extending through margins of said plate means and having end portions adapted for connection to a support;

(i) nuts on said through bolts on opposite sides of the plate means from the block and clamping the plate means and the block together;

(j) said bolts being effective to hold said block firmly in a lixed angular position between said caps, said angular position being universally variable by rotation of the block between the caps upon loosening of the nuts on the through bolts.

References Cited UNITED STATES PATENTS 2,477,648 8/ 1949 Piggot et al Z50-108 2,891,167 6/1959 Coleman et al. 250;-105 3,177,365 4/1965 Bozoki et al. 3,197,639 7/ 1965 Stone et al. 3,187,181 6/1'965 Keller. 3,272,987 9/1966 Kohn et al.

ARCHIE R. BORCHELT, Prim-ary Examiner SAUL ELBAUM, Assistant Examiner U.S. Cl. X.R. 250-106, 108 

